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de Castro A.,University of Santiago de Compostela | Lendoiro E.,University of Santiago de Compostela | Fernandez-Vega H.,University of Santiago de Compostela | Steinmeyer S.,Drager Safety AG and Co. KGaA | And 2 more authors.
Journal of Chromatography A | Year: 2014

Since the past few years, several synthetic cathinones and piperazines have been introduced into the drug market to substitute illegal stimulant drugs such as amphetamine and derivatives or cocaine due to their unregulated situation. These emerging drugs are not usually included in routine toxicological analysis. We developed and validated a LC-MS/MS method for the determination of methedrone, methylone, mephedrone, 3,4-methylenedioxypyrovalerone (MDPV), fluoromethcathinone, fluoromethamphetamine, 1-(3-chlorophenyl)piperazine (mCPP) and 3-trifluoromethylphenylpiperazine (TFMPP) in oral fluid. Sample extraction was performed using Strata X cartridges. Chromatographic separation was achieved in 10min using an Atlantis® T3 column (100mm×2.1mm, 3μm), and formic acid 0.1% and acetonitrile as mobile phase. The method was satisfactorily validated, including selectivity, linearity (0.2-0.5 to 200ng/mL), limits of detection (0.025-0.1ng/mL) and quantification (0.2-0.5ng/mL), imprecision and accuracy in neat oral fluid (%CV=0.0-12.7% and 84.8-103.6% of target concentration, respectively) and in oral fluid mixed with Quantisal™ buffer (%CV=7.2-10.3% and 80.2-106.5% of target concentration, respectively), matrix effect in neat oral fluid (-11.6 to 399.7%) and in oral fluid with Quantisal™ buffer (-69.9 to 131.2%), extraction recovery (87.9-134.3%) and recovery from the Quantisal™ (79.6-107.7%), dilution integrity (75-99% of target concentration) and stability at different conditions (-14.8 to 30.8% loss). In addition, cross reactivity produced by the studied synthetic cathinones in oral fluid using the Dräger DrugTest 5000 was assessed. All the analytes produced a methamphetamine positive result at high concentrations (100 or 10μg/mL), and fluoromethamphetamine also at low concentration (0.075μg/mL). © 2014 Elsevier B.V.. Source

de Castro A.,University of Santiago de Compostela | de Castro A.,Cienytech S.L. | Lendoiro E.,University of Santiago de Compostela | Fernandez-Vega H.,University of Santiago de Compostela | And 3 more authors.
Drug Testing and Analysis | Year: 2014

Since the implementation of mandatory drug testing in drivers' oral fluid, several solutions to avoid an onsite positive result can be found on drug users' forums, especially for marijuana, including the use of different mouthwashes. Recently, a product for personal hygiene, Kleaner, has been sold for this purpose. The aims of this study were to assess the effect of water, whole milk, and Kleaner mouthwashes on tetrahydrocannabinol (THC) oral fluid concentrations, and those observed in passive smokers subjected to extreme contamination conditions. The study was performed on four days. On day 0, study information was given to the participants. On days 1, 2, and 3, 11 chronic cannabis users smoked their usual daily dose, and oral fluid specimens were collected before smoking (t=-0.5h) and at t=0.25, 0.5, 1, 3, 6, 12, and 24 h post-smoking. On day 1, participants rinsed their mouth with water before each specimen collection. On day 2, 5 participants rinsed their mouth with Kleaner and 6 with whole milk. On day 3, a specimen was collected before and after rinsing the mouth with water. Statistically significant lower concentrations were observed comparing concentrations in oral fluid specimens collected before and after a water rinse. However, maximum THC concentrations at t=0.25h were >3-fold higher than the cut-off employed by the Spanish police (25 ng/mL) regardless of the use of any mouthwash. THC was also detected in the oral fluid of passive smokers subjected to extreme contamination conditions; however, concentrations were <25 ng/mL in all cases. © 2014 John Wiley & Sons, Ltd. Source

Ziegler M.,University of Kiel | Harnack O.,Drager Safety AG and Co. KGaA | Kohlstedt H.,University of Kiel
Solid-State Electronics | Year: 2014

Resistive switching in lateral tunnel junctions is reported. Nanogap tunnel junctions made of Au/SiO2/Au and Au/TiO2/Au were patterned by electrical-beam-lithography (EBL) and a controlled electromigration process. Depending on the substrate material, different reproducible resistive switching characteristics were observed under vacuum conditions. While for TiO2 substrates bipolar resistive switching was observed, nanogap junctions on SiO2 substrates showed resistive switching characteristics with a negative differential resistance. The role of the substrate material with respect to the resistive switching behavior is discussed in the framework of the electrical breakdown. All experiments were performed under vacuum to suppress parasitic effects due to charged particles in ambient air. Nanogap resistive switching devices are promising candidates for densely integrated memresistive systems such as non-volatile resistive random memories (RRAMs), field programmable arrays (FPGAs), or artificial neural networks (ANNs). © 2013 Elsevier Ltd. All rights reserved. Source

Nather C.,University of Kiel | Wohlert S.,University of Kiel | Boeckmann J.,Drager Safety AG and Co. KGaA | Wriedt M.,Clarkson University | Jess I.,University of Kiel
Zeitschrift fur Anorganische und Allgemeine Chemie | Year: 2013

In this report a rational route to coordination polymers that can show cooperative magnetic phenomena is presented. In this approach compounds based on transition metal cations, small sized terminal N-bonded anionic ligands and additional neutral N-donor co-ligands are heated, which lead to the formation of intermediates, in which the metal cations are linked by the anionic ligands. Predominantly, the use of this method for the synthesis of bridged thio- and selenocyanato coordination compounds is described in this article but it can also be extended for the preparation of other compounds. In most cases the intermediates are formed in very pure form and in quantitative yields. Thus, compounds, which are not or at least very difficult to obtain, can be prepared if the synthesis is performed in solution. This is especially valid for thio- and selenocyanato coordination compounds, which mostly prefer terminal bonding instead of bridging coordination with less chalcophilic metal cations like e.g. MnII, FeII, CoII, or NiII. It is demonstrated how 1D and 2D networks can selectively be prepared and that this method is predestinated for the synthesis of compounds that show a slow relaxation of the magnetization. A large number of compounds were investigated in which the metal cation, the anionic ligand, or the neutral co-ligand is exchanged, which allowed the study of structure-property relationships. Further investigation showed that these reactions can proceed via several different intermediates. At first glance one disadvantage of this approach might be that the intermediates isolated consist of microcrystalline powders, which structurally are difficult to characterize. However, different possibilities are presented to overcome this problem including investigations of analogous compounds based on diamagnetic cadmium cations, which in contrast to the paramagnetic metal cations prefer a bridging coordination of the anionic ligands. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Nauber A.,Dragerwerk AG and Co. KgaA | Tschuncky P.,Drager Safety AG and Co. KGaA
ECS Transactions | Year: 2013

Reliable detection of low level toxic gas impurities in breathing air is one of the challenging tasks in Dräger products. Among our detector portfolio electrochemical sensors belong to our key technology, which we try to improve continuously in terms of sensitivity, selectivity and stability. Ionic Liquids offer the advantages of displaying a huge electrochemical open window with negligible background currents. They can be designed task specific for the application they are used in and besides outstanding chemical inertness they offer the intrinsic advantage of being nonvolatile, which makes it possible to construct sensors that even can be used under zero humidity conditions which e.g. can be found for H2S monitoring in deserts e.g. in oil fields. © 2014 The Electrochemical Society. Source

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